1. Technical Field of the Invention
The present invention relates to a technology to measure a micro surface shape of an object to be measured. More particularly, the present invention relates to a micro surface shape measurement probe capable of minutely adjusting a contact pressure between a probe member and an object to be measured. Furthermore, the present invention relates to a micro force measurement device capable of measuring a micro force in order to minutely adjust a contact pressure.
2. Description of the Related Art
A technology to measure a shape of an object to be processed on a processing machine, a so-called on-machine measurement technology is indispensable in performing highly precise processing. This on-machine measurement technology can not only eliminate a positioning error during attachment/detachment of the object to be processed but also save labor hours necessary for arrangements during the attachment/detachment work to achieve improvement of a processing efficiency and automation at the same time.
As a device for measuring the shape of the object to be processed, there has heretofore been known a probe type shape measurement sensor in which a distant end of a measurement probe is brought into contact with the surface of the object to be processed to measure the shape of the object (e.g., Patent Document 1).
During such surface shape measurement, in general, the smaller a contact pressure is, the more precise surface shape measurement can be performed.
[Patent Document 1]
International Patent Publication No. WO00/52419 “Probe Type Shape Measurement Sensor, and NC Processing Device and Shape Measurement Method using the Sensor”
However, in the conventional technology, in order to bring the probe distant end into contact with an object to be measured, the probe is pressed, moved and brought into contact with the object to be measured by a pneumatic pressure or the like, but this adjustment of a pressing force has a limitation of about 50 mgf. Such a technology to adjust the pressing force by such a pneumatic pressure is described in Patent Document 1 described above.
Moreover, even when a method of adjusting the pressing force by the pneumatic pressure is devised so as to increase a control resolution of a regulator or perform a multistage control, there is a problem that the device becomes larger in size or a stable operation is not easily performed.
Therefore, it has been difficult to adjust the contact pressure further minutely below 50 mgf. This has been a factor for determining a limitation of the precision of micro surface shape measurement.
Furthermore, the following factors inhibit precise surface shape measurement.
In a case where the probe distant end is brought into contact with the object to be measured, when the surface of the object to be measured is inclined with respect to the probe distant end, there has been a problem that a probe shaft is laterally displaced. In a case where the probe distant end is formed into a spherical shape, when this distant end ball is attached to a shaft portion of the probe, there has been a problem that an attachment error is generated.